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Polycyclic aromatic hydrocarbons (PAHs) belong to the persistent organic pollutant class and are ubiquitously present in the environment. As a consequence of their high hydrophobicity, PAHs in aquatic environments tend to rapidly sink down to the bottom sediments which are the most important reservoirs of PAHs in the aquatic environment. This paper presents the validation and further performance evaluation of a method modified in-house for PAHs' sample preparation and analysis in sediment using gas chromatography-mass spectrometry (GC-MS). The method validation covers determining the calibration linear range, method detection and quantitation limits, method recovery and precision, method uncertainty and further internal and external quality control steps. Principal component analysis was used to identify the influence of different variables on method performance and indicated main clustering by PAH molecule size. The results of a two-year quality control programme show that the variations in method performance were not statistically significant in comparison to the parameters set during the validation experiments. Trueness expressed as recovery was very similar for spiked sediment samples and the analysed certified reference material (CRM) (70.6–113%). Expanded uncertainty ranged from 40.4% to 50.9% with higher values noted for the highly hydrophobic PAHs benzo(a)pyrene and benzo(g,h,i)perylene. [ABSTRACT FROM AUTHOR]

This study assesses the spatial distribution and contamination level of heavy metals in Safi Bay surface sediments. In this order, 28 surface sediment samples were retrieved from the study area and analyzed using the x-fluorescence method. To assess the contamination of the examined sediment, we used geo-ecological indices such as contamination factor (CF), degree of contamination (DC), geo accumulation index, and pollution load index (PLI). The results show that only Pb and Cd present moderate and considerable contamination in some sampling sites, while other elements (Cr, Cu, Zn, and Ni) indicate no contamination and low contamination by these elements. The inhomogeneous distribution of metal concentrations along the bay suggests different heavy metal sources. Given the ecological and socioeconomic importance of the study area, there is a need for a further analysis of both sediments and biological samples for a better understanding of the contamination levels and origin of metals, in addition to the sustainability of Safi Bay. [ABSTRACT FROM AUTHOR]

The arid region of Mongolia is sensitive to climate change. Understanding of climate variations in the past plays an important role in predicting further climate changes. In this study, we aim to investigate the relationship between the climatic factor and sedimentation history in the late Holocene. We analyzed the 18TS1 core sample (136 cm in length) from the Tsagaan lake in the Valley of the Gobi Lakes, Mongolia. The sediment core mainly consists of clay and silt sediments, occasionally interrupted by the sand-dominated layers. 210Pb dating method is applied and indicates that the upper 24 cm sediment spans the sedimentation history of the last 87 years. Along-core variations in sediment characteristics such as organic matter, carbonate, and amorphous silica abundance are indicative of the drought -inducing period based on the significant correlations between sediment characteristics and Self-calibrated Palmer Drought Severity Index. Moreover, the enrichment of carbonates is a great indicator of shallow lake conditions prior to the lake disappearance during the dry period. The chemical composition of sand-dominated units in the sediment core well agrees with that of sand sheets and sand dunes in the catchment. Modern expansion and migration of sand sheets are identified by aerial photo imagery. The insufficient sediment chronology is limiting our interpretation, though; the comparison with the other paleoclimate records helps the establishment of environmental changes in the last millennium. [ABSTRACT FROM AUTHOR]

The Paisley Cave archeological site in the Northern Great Basin has provided a rich archaeological record from 13,000 to 6000 cal yr BP, including abundant mammalian coprolites preserved in a well-dated stratigraphy. Here we analyze and contrast pollen from within coprolites and pollen in associated sediments to examine vegetation history and assess whether coprolite pollen provides unique information with respect to the coprolite producer, such as the use of specific habitats, foods, or water sources. We found that the dissimilarity of pollen assemblages between coprolites and associated sediments was greater than the serial dissimilarity between stratigraphically adjacent samples within either group. Serial dissimilarity within types was not greater for coprolites than sediments, as would be expected if there were unique pollen signatures derived from the short period (1–2 days) represented by each coprolite. Compared with sediment pollen assemblages, the coprolites had higher abundances of lighter pollen types, and some individual samples were high in wetland taxa (especially Typha). Our results are consistent with coprolite pollen representing short time periods collected as a mammal moves on the landscape, whereas sediment pollen reflects longer time periods and more regional vegetation indicators. [ABSTRACT FROM AUTHOR]

The water and sediment characteristics of the Yellow River are related to the development of the river basin and have great significance in determining the future trends in sediment load. In this study, the water and sediment characteristics and influencing factors were analyzed. The correlations among hydrological and sediment parameters were further analyzed. The results showed that the annual average sediment concentration (AASC), the annual sediment load (ASL), the median grain size of sediment (MGSS) and the annual sediment transport modulus (ASTM) decreased. Therefore, the sediment control effect of the tributaries was significant. The annual runoff (AR) of the hydrological stations in the Yellow River increased from 2002 to 2019. Altogether, AASC and ASL of the Yellow River showed a downward trend. The sediment was reduced by water storage and sediment detention of reservoirs. AASC and ASL increased significantly due to water and sediment regulation tests and floods. However, the silt in the river channel could be washed with the help of current scouring and flood to slow down the silt. There was a strong correlation between AASC and ASL, whether the Yellow River or its tributaries. Besides, there was a significant impact of AASC and ASL of the tributaries on the sediment of the Yellow River, showing that the sediment control of the tributaries was essential. The sediment in the main tributaries and the Yellow River showed a decreasing trend from 2002 to 2019, which is conducive to the ecological harmony and stability of the Yellow River. [ABSTRACT FROM AUTHOR]

The level of metallic (Cd, Ni, Fe, Pb, Cu) contamination in the sampled sediments of five stations (S1, S2, S3, S4 and S5) from Woji creek bed between August and October 2019 was appraised using pollution load index (PLI), contamination factor (CF) and geoaccumulation index (Igeo). Results from the sediment analysis showed that Cd was not detected in stations 1, 3 and 5 in September, however, there was a high concentration of Cd in station 3 in October (43.590 ± 2.013 mg/kg). The concentration of Ni was highest in station 4 in August (247.682 ± 6.026 mg/kg). The mean spatial concentration of Pb ranged from 57.774 ± 75.647 mg/kg in October to 344.153 ± 112.184 mg/kg in August. Spatially, the highest concentration of Fe was measured in August (23.945 ± 17.828 mg/kg). Station 2 had the lowest concentration of Fe in the sediment temporally (5.667 ± 6.381 mg/kg) while station 3 had the highest concentration (19.496 ± 24.090 mg/kg); 37.188 ± 27.821 mg/kg (station 3) was the highest mean temporal concentration Cu, while station 2 had the lowest mean concentration of Cu (0.471 ± 0.358 mg/kg).The PLI values were in the trend: S3 (2.58 x 1015) >S4 (5.29 x 1014) > S1 (3.52 x 1014) > S5 (3.71 x 1013) > S2 (4.64 x 1012).These results indicated that the highest concentration of studied metals was found in S3 (except for Ni in S4), which emphasised the possible input of metallic matter into the sediment from the various operations along the creek connected with the disposal of metallic particulate wastes. All the metals present in the sampled sediments (except for Cu in S2) had concentrations between threshold effect level (TEL) and probable effect levels (PEL), which suggests the influence of unfavourable biological processes taking place from time to time. [ABSTRACT FROM AUTHOR]

As one of the most important margin seas around the west Pacific, the eastern China seas are important sink for terrigenous materials and forms multiple geology structures. So research the composition and spatial distribution of sediments could help us to understand the dynamics mechanism of the marine sedimentary environment, further to comprehend the land-sea interaction process. Based on high spatial resolution sediment survey in the eastern China seas, the distribution diagram of the sediment types was compiled to reveal the space regularities of sediment. In this study, the Principal Component Analysis (PCA) method was used to identify the controlling factors that are the main controls of the sediment distribution in the study area, which revealed three factors (F1, F2 and –F1) representing grain size categories of >5.75φ, 4.25–5.75φ and 1.50–3.00φ, respectively. F1 represents fine sediments (>5.75φ), -F1 represents coarse sediments (1.50–3.00φ), and F2 represents intermediate-sized sediments (4.25–5.75φ). The sediment transport patterns of the different grain size categories in the eastern China seas are discussed in the context of a comprehensive analysis of sediment grain size composition, material sources, flow patterns, and other factors. The results show that fine-grained sediments represent a "distant" sink of terrigenous material that formed in a stable and low-energy sedimentary environment. The coarse sediment deposits were formed in the late Pleistocene when the hydrodynamic conditions were relatively strong, and the intermediate-sized sediments were distributed in an area with a high concentration of suspension representative of mid-strength hydrodynamic conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

As an important source, sink and pool of carbon, lake sediment plays an important role in carbon cycle. Inorganic carbon (IC) in lake sediment is abundant, however the role of inorganic carbon in lake systems in terrestrial carbon cycling remains less clear. In this paper, the spatial variations, source and transformation of IC in sediments of Lake Hulun were investigated and compared with typical lakes of Inner Mongolia Plateau by analyzing the influencing factors. The results showed that contents of total IC in surface sediment in Lake Hulun ranged from 17.2 to 66.7 mg g–1 with a mean of 42.6 mg g–1, and the pattern of spatial distribution showed obviously decreasing trend from southwest to northeast lake districts. The order size of IC fractions in surface sediment was in a sequence of EX (extracted by NaCl) < SAL (extracted by NaOH) < WAL (extracted by NH3·H2O) ⪡ SAC (extracted by HCl) < WAC (extracted by HO-NH2·HCl), the WAC and SAC fractions were the major fractions, accounted for 80% of total IC. In vertical distribution, the WAC and SAC fractions presented obviously opposite spatial distribution, indicted that these fractions could transform into each other in sediments. The ratio of IAP/Ksp in lake water ranged from 8.87 to 108.5, suggested that this lake had what it took to form the authigenic carbonate precipitation. A differential analysis study indicated that the mechanisms what made the difference of IC content in four lakes were multiple, the chemical properties and temperature of lake water, the defusion or dissolve of CO2, biomass and sediment environment were the key factors that might affect the contents of inorganic carbon in the lake sediment. [ABSTRACT FROM AUTHOR]

Assessing microbial identity, diversity, and community structure could be a valuable tool for monitoring the impact of xenobiotics and anthropogenic inputs in rivers, especially in urban and industrial settings. Here, we characterize the Nile River microbial community in water and sediments in summer and winter at five locations that span its natural flow through the Cairo metropolis. 16S rRNA gene datasets were analyzed to identify the role played by sample type (sediment versus water), season, and location in shaping the community, as well as to predict functional potential of the Nile River microbiome. Microbial communities were mostly influenced by sampling type (sediments versus water), while seasonal effects were only observed in water samples. Spatial differences did not represent a significant factor in shaping the community in either summer or winter seasons. Proteobacteria was the most abundant phylum in both water and sediment samples, with the order Betaproteobacteriales being the abundant one. Chloroflexi and Bacteroidetes were also prevalent in sediment samples, while Cyanobacteria and Actinobacteria were abundant in water samples. The linear discriminative analysis effect size (LEfSe) identified the cyanobacterial genus Cyanobium PCC-6307 as the main variable between summer and winter water. Sequences representing human and animal potential pathogens, as well as toxin-producing Cyanobacteria, were identified in low abundance within the Nile microbiome. Functionally predicted metabolic pathways predicted the presence of antibiotic biosynthesis, as well as aerobic xenobiotic degradation pathways in the river microbiome. [ABSTRACT FROM AUTHOR]

The excessive use of pesticides has become a global concern owing to the great adverse effect exerted on human health and the environment. The application of Soxhlet extraction (SE) and accelerated solvent extraction (ASE) techniques to the analysis of 15 organochlorine pesticides (OCPs) in sediment samples was described. Sediment samples were obtained from the Vaal River, the largest tributary of the Orange River in South Africa. The method detection limit (MDL) is in the range of 0.01 to 0.25 mg/L, and the average recoveries were in the range 63.2 %- 96.0% with standard deviations in the range 3 %-12.5 %. The total OCPs are in the values of 0.352 μg/L, 0.352 μg/L, and 0.212 μg/L in the sediments from Vereeniging, Barrage, and Parys respectively using the ASE method. Higher values of 4,4ʹ-DDE, 4,4ʹ-DDD, and 4,4ʹ-DDT were found in samples collected from Vereeniging and Barrage locations within the range 0.068-0.095 μg/L and 0.063-0.089 μg/L respectively. The mean concentrations of OCPs residues in the sediment samples follows the order: endosulfan I > 4,4ʹ-DDT > 4,4ʹ-DDE > 4,4ʹ-DDD > α- HCH > β-HCH > heptachlor epoxide > trans-chlordane > γ-HCH heptachlor. It was revealed that the ASE was the optimal technique for the analysis of OCPs in sediments. It can be concluded that the accelerated solvent extraction (ASE) is an effective extraction technique for the analysis of organochlorine pesticides from sediment matrices within a short period, and consumes less solvent. [ABSTRACT FROM AUTHOR]

This paper analyzes the mass fractions of Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Nd, Rb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn determined from sixty sediment samples obtained from the Lapa Grande de Taquaraçu archaeological site using instrumental neutron activation analysis, INAA. The archaeological site is located in the municipality of Jaboticatubas, about 60 km from Belo Horizonte, Minas Gerais State, Brazil. The dataset was explored by means of cluster analysis, principal component analysis and discriminant analysis. The study showed three different compositional groups related to anthropogenic sediment, fluvial system and oxisols, respectively. The crystalline structure of each group were studied using X-ray diffraction, XRD. [ABSTRACT FROM AUTHOR]

It is a good method to utilize the grain size distribution curves and cumulative frequency curves of marine or river sediments to estimate the hydrodynamic conditions, transportation processes and sedimentary environment. However, researchers can only rely on Excel or Grapher to plot the curves one by one at the present day. The manual plotting procedures are complicated, and calculating the truncation points is time-consuming. To solve the aforementioned problems, we have developed a software tool to plot cumulative frequency curves and calculate the values of truncation points automatically. The software has the ability to plot curves of hundreds of samples accurately and rapidly, promoting researchers to analyze transport mechanisms and hydrodynamic environments. And it is convenient to apply the software to compare the processes of transportation and deposition between different samples. [ABSTRACT FROM AUTHOR]

The text of this contribution provides a comprehensive summary of the issue of sedimentation. In the descriptive part of the paper, the issue of pond sedimentation is analyzed from both the quantitative and the qualitative point of view. The experimental part is subsequently focused on the quality of pond sediment. Detailed attention is given to land use and the quality of soil on adjacent agricultural land and their influence on sediment quality. The paper is unique in providing detailed monitoring of sediments and adjacent agricultural land at a selected pilot location, which is characterized by intensive agricultural use and by the presence of numerous water bodies (ponds used for semi-intensive fish breeding). The paper presents in detail results obtained from a laboratory analysis, especially concerning contamination by risk elements and foreign substances. Laboratory results are further compared against Czech legislation dealing with the reapplication of sediments on agricultural land. Lastly, the paper deals with the nutrient potential of sediments and with the potential impacts of their application on agricultural land. [ABSTRACT FROM AUTHOR]

A new in situ radioactivity analysis method was developed to determine the fractional contributions of gamma-ray emitters in seawater and sediment from total measured counts. A semi-empirical formula to determine the fractional count contributions was derived using the variation characteristics of the gamma-ray attenuation rate and geometrical efficiency with the measurement points. The proposed method was employed to make in situ gamma-ray measurements using a CeBr3 detector for radioactivity analysis of seawater and sediment at a coastal area with a relatively high tidal range. The full energy peak efficiency of the detector at measurement site was obtained using the GEANT4 simulation code. The radioactivity concentration of 40K in seawater and sediment was determined using the proposed method and laboratory analysis with sampling. The MDA of the in situ measurement for 137Cs and 131I was also estimated assuming they were deposited on the sediment surface-layer. The validation of this method was demonstrated by comparing with the sampling analysis results. [ABSTRACT FROM AUTHOR]

Luminescence holds unique potential as a sediment tracer and provenance method. The tracer application of luminescence has key advantages including ease of measurement, relatively low cost, and applicability to geologically ubiquitous quartz and feldspar sand and silt. These advantages can help answer fundamental questions about geomorphology, sediment transport, sediment production, and the tectonic/climatic controls on source‐to‐sink sedimentary systems. There is a notable body of research on luminescence as a sediment tracer. These tracer methods range from identifying source locations based on unique luminescence characteristics, to observing changes in luminescence characteristics with transport, to using residual luminescence to infer rates of transport. Previous applications of luminescence include provenance and quantification of fluvial transport rate, tracing of coastal longshore drift, estimations of mixing rates in soil or sediment, and provenance of wind‐blown deposits. The few studies that compare luminescence methods with nonluminescence tracer methods show good agreement. However, more work is needed to test the application of luminescence tracers in sediments. Future research directions should focus on comparing luminescence‐based with nonluminescence tracer methods. Furthermore, research is needed on the effects of specific geomorphic processes on luminescence characteristics and residual doses. While there is significant potential for future research, luminescence is already a useful sediment tracer and provenance tool applicable to a wide range of geomorphic environments. Plain Language Summary: We live on a surface that is constantly changing. These changes occur as sediment is moved around by various forces in the environment. We want to be better able to predict sediment movement so we can minimize its negative effects. Examples of these negative effects include erosion of soil on farms, filling of reservoirs we use for water with sediment, and pollution of sediment in waterways and ecosystems. To get better at predicting negative effects, we need to know how fast sediment moves and where it comes from. Some techniques scientists use to answer these questions include using unique properties of sand grains to track their movement. However, there is not a technique that works for every environment, so we have to develop new techniques to expand our capability. In this paper, we review the use of luminescence, a property that changes in sunlight, to track the movements of sediment. Luminescence is not commonly used as a sediment tracker but shows lots of potential. We outline the past uses of luminescence as a sediment tracker and describe the future research that is needed to improve its use as a tool for scientists. Key Points: Luminescence, a property of matter often used for dating, can also be used as a sediment tracer and sediment fingerprinting toolWe review previous research on luminescence sediment tracing/fingerprinting and show that there is a significant body of researchThere is potential to expand and develop the luminescence sediment tracing/fingerprinting method to various geomorphic environments [ABSTRACT FROM AUTHOR]

Phytoliths are essential palaeoecological proxies that play an immensely important role in palaeoclimatic studies. Their inert composition and general hardiness allow phytoliths to be preserved in geological settings, even when other plant fossils perish. This partially explains their utility for investigating plant communities and plant-human interactions on short and long timescales. Phytoliths also happen to be the most reliable source of fossil evidence for tracking the evolutionary history of grasses, arguably among the most crucial extant plant families. In the last two decades, the number of studies and publications in all fields of phytolith analysis has grown exponentially, mainly due to a diversification of research topics. Although significant progress has been made in applying phytolith analysis to answer archaeological, palaeoenvironmental, palaeoclimatological, evolutionary, and taxonomic questions, phytolith assemblages can be subject to pre- and post-depositional processes that might affect their preservation and thus could bias interpretation. This article reviews the importance of phytolith research in palaeoecology, discusses the constraints and taphonomic processes affecting phytolith analysis, and highlights the challenges in phytolith studies across various sediments. It emphasizes the significance of identifying phytolith transportation modes and understanding the impacts of taphonomic processes. Specific sampling strategies, such as targeting environments protected from surface weather conditions and selecting sediments with lower translocation rates or little horizon development, are suggested to preserve a diverse range of phytolith morphotypes. Caves and deltas are proposed as suitable alternatives to neritic marine sediments and carbonate-rich sites. This review also emphasizes the importance of sediment analysis, including grain size, sediment transport trend analysis, and micromorphology, complemented by analytical techniques and multi-proxy approaches. The inclusion of thin section studies, micromorphology, SEM, EDS, FT-IR, XRD, AAS/AES, XRF, and ICP-MS/AES is recommended to minimize depositional biases and help understand biases related to phytolith formation. Using mathematical models and correlation measurements to assess the impact of taphonomy on phytolith assemblages is also valuable. To conclude, we discuss some analytical considerations and suggest a methodological framework that integrates phytolith analysis with a sedimentological perspective. This approach aims to minimize the biases in phytolith analysis and enhance our understanding of palaeoecology. [ABSTRACT FROM AUTHOR]

The use of per- and polyfluoroalkyl substances (PFAS) containing aqueous film forming foams (AFFF) at fire training facilities can have an adverse impact on the surrounding environment. The aim of the present study was to study the distribution and temporal trend of 26 PFAS in water and sediment cores for a lake and a pond affected by AFFF release from a fire training facility in Luleå, northern Sweden. In the aqueous phase, maximum ΣPFAS concentration was 1.700 ± 90 ng L−1. Dominant PFAS groups were perfluoroalkane sulfonates (PFSAs) with 70% of the ΣPFAS, followed by perfluoroalkyl carboxylates (PFCAs, 29%), whereas the contribution of 6:2 fluorotelomer carboxylate (FTSAs) was low (<1%). In the sediment core samples, ΣPFAS concentrations ranged between <1 μg kg−1 dry weight (dw) and 76 μg kg−1 dw, where perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) had an average contribution of ∼71% and ∼23% of the ΣPFAS. The sediment core analysis indicated that the PFAS contamination began about 1994 and the highest accumulation rate was observed for the period 2003–2009. The PFAS flux increased from 2.3 μg m−2 yr−1 dw in 1994 to 12 μg m−2 yr−1 dw by 2009. Over the accumulation period 1994–2009, the lake sediment surface received 213 μg m−2 dw for ƩPFAS, where PFOS contributed with 125 μg m−2 yr−1 dw and PFHxS with 65 μg m−2 dw. Results point to that sediment cores collected near PFAS hotspot areas can be used as a contamination record to reconstruct release history. • Sediment cores provided historical records for PFAS contamination. • Highest accumulation rate in sediment was observed for 2003–2009 period. • PFHxS and PFOS positively correlated to organic carbon fraction. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the interactive effects of oil contamination and chemical dispersant application on bacterial composition and sediment remediation of an estuarine port environment. Methods and Results: A multifactorial controlled microcosm experiment was set up using sediment cores retrieved from an estuarine port area located at Ria de Aveiro lagoon (Aveiro, Portugal). An oil spill with and without chemical dispersant addition was simulated. Sediment oil hydrocarbon concentrations and benthic bacterial community structure were evaluated by GC‐MS and 16S rRNA high‐throughput sequencing respectively. Although initially (first 10 days) chemical dispersion of oil enhanced the concentrations of the heavier polycyclic aromatic hydrocarbons and of the C22‐C30 alkane group, with time (21 days), no significant differences in hydrocarbon concentrations were detected among treatments. Moreover, no significant changes were detected in the structure of sediment bacterial communities, which mainly consisted of operational taxonomic units related to hydrocarbon‐contaminated marine environments. We hypothesize that the environmental background of the sampling site preconditioned the communities' response to additional contamination. Conclusion: This experimental microcosm study showed that the chemical dispersion of oil did not influence sediment remediation or bacterial community composition. Significance and Impact of the Study: Our study showed that chemical dispersion of oil may not improve the remediation of port sediments. Further studies are needed to investigate the impact of chemical dispersants in combination with bioremediation strategies on the process of sediment remediation in port areas. [ABSTRACT FROM AUTHOR]

In order to study the effect of reed and cattail on the bacterial community structure of surface sediments of wetland in winter, high-throughput sequencing technology was used to analyze the bacterial composition. The results showed that 134 228 high-quality gene sequences were obtained by high-throughput sequencing in sediments of natural wetland in winter, and there were 13 866 OTUs, in which the number of OUT in sediments of reed wetland and cattail wetland was 6 677 and 7 189 respectively. The richness and diversity of bacterial communities in sediments of cattail wetland in winter were higher than those in sediments of reed wetland. Relative abundance of Proteobacteria in sediments of reed wetland and cattail wetland was 0.54 and 0.52, respectively. The dominant classes of bacteria were Betaproteobacteria, Deltaproteobacteria, Gammaproteobacteria and Epsilonproteobacteria, which belonged to gram-negative bacteria, indicating that the rhizosphere of wetland was easier to enrich gram-negative bacteria. Under the genus level, the dominant bacteria in the sediments were not obvious. [ABSTRACT FROM AUTHOR]

Abstract The condition of Baiyangdian Lake (BYDL) will improve as the Xiongan New Area evolves and fulfills its role of easing overcrowding and supporting economic growth. Water and sediment samples from BYDL were analyzed to provide information on nitrogen (N) contamination in BYDL. The mean ammonium N (NH 4 +-N), nitrate N, and total N concentrations in the water samples were 0.36, 0.12, and 2.22 mg/L, respectively, and the ranges were 0.003–8.38, 0.06–0.30, and 1.25–10.34 mg/L, respectively. The N concentrations in water gradually increased from the north to the south of BYDL. Sediment at 90% of the sampling sites was in or above the moderately contaminated class (1000–2000 mg/kg) defined in US Environmental Protection Agency total N pollution standards. Positive NH 4 +-N fluxes were found for 28 of the 34 sediment core samples, so the potential for NH 4 +-N being released from sediment was relatively high. The NH 4 +-N fluxes were 5.35–48.76 mg/m2/day, and the mean and maximum fluxes were 8.71 and 48.76 mg/m2/day, respectively. Benthic organisms will be affected more by NH 4 +-N and NH 3 ·H 2 O in the surface sediment pore water (mean concentrations 4.93 and 0.13 mg/L, respectively) than by the other forms of N. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Sediments composed of oil-particle aggregates (OPAs) have unique physical characteristics. These in situ deposited sediments develop at locations where a continual or nearly continual discharge of non-aqueous phase liquids (NAPLs) have occurred, or are occurring through time. The NAPL discharged into the surface water body interacts with suspended particles in the water column. The particles adhere to the suspended NAPL, which generally is in the form of a bead, and produce a discrete aggregate. As the aggregate grows in response to additional particle adherence, the density of the unit increases and deposition occurs. The resulting sediment consists of a collection of discrete OPAs that form a network with small pores, where oil is tightly bound and/or contained. Porosity, water content, and dry bulk density measurements indicate the sediment formed by OPA deposition is physically unique. Although the sediment consists of a very open pore structure, the pore openings are relatively small, typically being less than 5 microns in diameter. These small pores inhibit fluid movement. Results of physical property testing suggest the OPA structure is retained upon deposition. Although the sediment contains NAPL, this original OPA structure inhibits the oil beads from coalescing, which would enable NAPL flow. [ABSTRACT FROM AUTHOR]

The temporal variation of sulfur and metals in core sediments off Kueishantao Islet, a hydrothermal vent site at northeastern Taiwan, was explored to elucidate the changes in submarine hydrothermal emanation over a centennial time scale. The discharge of acidic fluids containing abundant sulfides and dissolved metals results in different concentrations of sulfur and metal accumulating in deposited sediments. In addition to particle size and organic carbon affecting metal contents, the content of total sulfur (TS), which is regarded as an indicator of hydrothermalism, correlates positively and strongly with Fe and other metals; however, it correlates negatively with another index of hydrothermalism, the Al/(Al+Fe+Mn) ratio. The TS content in Core Ks2, the core closest to the vents, increased during 1950–1956, 1968–1970, 1982–1987, 1990–1992, and 2004–2005, but decreased during 1967–1968, 1988–1990, and 1994–1995. The chronological changes in the TS concentration of Cores Ks3 and S2 were very similar to those of Core Ks2 within the aforementioned time spans. The numerous large earthquakes (ML > 5) and typhoons that affect northeastern Taiwan appear to influence hydrothermal emanation and determine the temporal variation of sulfur and metals in sediment cores. [ABSTRACT FROM AUTHOR]

This study was performed to determine the distribution and chemical fractions of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in sediment from three sampling areas in Swan Lagoon, and their relation to the physiochemical properties of sediment were explored. The results revealed that Cd in sediment from the sand part (SP), muddy sand part (MSP) and sand muddy part (SMP) were potentially highly susceptible and bioavailable since the exchangeable fractions were 21.0%, 27.4%, and 32.1%, respectively, of the total concentrations. A portion of Pb and Zn were observed as reducible fractions owing to their affinity to Fe-Mn; they were able to complex with Fe-Mn oxides and oxyhydroxides in the sediment. A large amount of Cu in the oxidizable fraction may be due to the fact that Cu can easily form stable complexes with organic matter. Cr was overwhelmingly found in the residual fraction, suggesting that Cr was strongly bound in mineral lattices. Enrichment factors (EF) indicated that Cd in three sampling areas suffered severe enrichment, whereas other metals were present in only minor amounts. In addition, Cd may pose a medium to high risk in the MSP and SMP based on risk assessment codes. According to the mean probable effects level quotient, the samples from the MSP and SMP had a 21% probability of toxicity. The multivariate statistical analysis suggested that sediment texture (d0.5, sand and silt), Fe-Mn, and the total organic carbon (TOC) influenced the distribution of the studied metals and their chemical fractions. [ABSTRACT FROM AUTHOR]

Several key aspects for the analysis of inositol hexakisphosphate (InsP 6 ) have been investigated in order to establish a suitable method for the study of sediment samples from different aquatic systems. Apparent matrix effects for the ion chromatography electrospray ionization tandem mass spectrometric detection (IC-ESI-MS/MS) method were accounted for with a standard addition approach, which also compensated for variation in extraction efficiency. Several parameters of the extraction method were optimized to improve the extraction efficiency for different sediment types. We observed an improvement in the extraction efficiency between 18% and 720%. Finally, the method was used to gain first insights into the relevance of InsP 6 in two aquatic systems located at the German Baltic coastal area. InsP 6 was detected in several sediment samples with concentrations between 2.3 and 15.2 µg InsP 6 -P/g dry weight (DW). [ABSTRACT FROM AUTHOR]

Intermittent flow of headwaters occurs with increasing frequency in temperate regions over last decades. Here, we assessed the effects of rewetting process on benthic prokaryotic communities from the Breitenbach (Hesse, Germany) for 10 days following experimental drought of different duration and intensity, by measuring the abundance of selected prokaryotic groups and potential extracellular enzyme activities (EEA). Desiccation time and intensity affected the recovery of the microbial community structure and the utilization of organic substrates in sediments, but recovery differed among prokaryotic groups and enzymes. Prokaryotes grew moderately to levels above the initial wet state, whereas Alphaproteobacteria were promoted. The EEA increased rapidly with overshoots within the first days of rewetting indicating high activation after desiccation. The ratios between the EEA changed with the duration of desiccation indicating changes of macromolecular organic matter utilization. The prokaryotic community and its functions were still distinctly different from the initial stream situation, and thus no resilience could be considered after short time (10 days) of recovery from desiccation. We propose that desiccation effects might be enhanced, if desiccation events occur under the effect of changing climate more often, more regularly, and/or for longer time spans. [ABSTRACT FROM AUTHOR]

Intertidal mudflat systems are shaped by geological processes and an interplay of hydrodynamics, sediment availability and ecological processes. All around the world these systems are affected by relative sea level rise (RSLR), changing climate and by human activities such as sediment nourishments, dredging, hydrological engineering and bottom trawling. These kinds of perturbations cause changes in morphology and sediment composition which may cause shifts in the composition, spatial distribution and productivity of benthic communities. We analysed the spatial and temporal variability of the sediment grain size of more than 900 km 2 intertidal flats in the Dutch Wadden Sea in the period 2009–2019. The large scale coverage was achieved by yearly grid sampling at more than 4000 stations. Spatial panel data models were used to analyse changes in median grain size and mud content between years and to estimate the effects of resuspension due to wind and the accumulation of silt during summer. We show that between years the sediments of the intertidal flats changed synchronously throughout the study area and that the flats became coarser during the period 2011–2015 and muddier again between 2015 and 2019. The system wide changes and the absence of clear local deviations leads to the hypothesis that a large scale factor like changing hydrodynamic regime (e.g. due to RSLR), variability in the composition of suspended sediment in the North Sea or changing microphytobenthic productivity were causally involved in the coarsening of intertidal flats. Our data and analysis provides a base for further scientific enquiry but longer time series on higher temporal resolution of both sediment data and the physical and ecological environment are required. Models simulating the environment may provide further insight into possible development of sediment composition of the intertidal flats of the Wadden Sea. • For 11 years more than 4000 intertidal sediment samples were collected yearly. • The grain size of the intertidal flats changed synchronously throughout the area. • A large scale factor is likely the cause of the synchronous dynamics. [ABSTRACT FROM AUTHOR]

The sustainable management of dredged sediment from contaminated sites needs to consider the end-use of the treated sediment. In this regard, modifying conventional sediment treatment techniques to generate a product that is suitable for a range of terrestrial uses is necessary. In the present study, we evaluated the product quality of treated sediment as a potential plant-growth medium following the thermal treatment of marine sediment contaminated by petroleum. The contaminated sediment was subject to thermal treatment at temperatures of 300, 400, or 500 °C, and no, low, or moderate oxygen availability, and the resulting treated sediment was analyzed in terms of its bulk properties, spectroscopic properties, organic contaminants, water-soluble salts and organic matter, and the leachability and extractability of heavy metals. All operational combinations for the treatment process reduced the total petroleum hydrocarbon content of the sediment from 4922 mg kg−1 to lower than 50 mg kg−1. The thermal treatment process stabilized the heavy metals in the sediment, reducing the zinc and copper concentration by up to 58.9% and 89.6%, respectively, in the leachate from the toxicity characteristic leaching procedure. The hydrophilic organic and/or sulfate salt byproducts of the treatment were phytotoxic, but these can easily be removed by washing the sediment with water. By combining the sediment analysis results with experimental data from barley germination and early-growth tests, the end product was found to be of higher quality when higher temperatures and lower oxygen availability were employed in the treatment process. These findings demonstrate that it is possible to retain the natural organic resources of the original sediment by optimizing the thermal treatment, thus ensuring a suitably high product quality for use as a plant-growth medium. [Display omitted] • Quality of thermally treated marine sediment was comprehensively evaluated. • Oxygen availability and temperature strongly affect the treated sediment quality. • Thermal treatment stabilizes metals while producing water-soluble toxicants. • Water-washing post-treatment enables producing high-quality media for plant growth. • For product quality pyrolytic conditions are superior to oxidative conditions. [ABSTRACT FROM AUTHOR]

This paper presents the results of research into pathways leading to the production of methane (CH4) and carbon dioxide (CO2) in sediments of two eutrophic reservoirs (Maziarnia and Nielisz), located in south-eastern Poland. In seeking to identify the pathways in question, use was made of analysis of stable carbon isotopes in CH4 and CO2 dissolved in pore water. This determined that CH4 is mainly produced through acetate fermentation, though the hydrogenotrophic methanogenic process may also be of importance, especially in deeper layers of sediments. Both the presence of autochthonous organic matter and increased pH values are shown to favour acetate fermentation. In turn, methanogenesis in sediments is assessed as capable of accounting for the generation of a considerable amount of CO2. Indeed, the role of methanogenesis in CO2 production is increasingly important further down in the layers of sediment, where allochthonous organic matter is predominant. [ABSTRACT FROM AUTHOR]

Sediments of the Venice Lagoon down to 50 cm depth were investigated to assess sediment texture and metal contamination status, before the construction and activation of the MOSE system, which is intended to prevent the periodical flood events affecting the lagoon and the city of Venice. 380 cores were collected in shallow-water areas of the lagoon, and analysed along their vertical profile to determine grain-size distribution and concentrations of some major and trace elements (Al, As, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn), total carbon and organic carbon. Radionuclide analyses ( 137 Cs, 210 Pb) were performed on 15 cores in an attempt to establish sediment chronology and determine radionuclide inventories in erosional and depositional areas. On the whole-lagoon scale, strong depletion of particles <31 μm in diameter (from medium silt to clay fractions) was observed in sediments down to 10 cm depth in comparison to deeper layers. This depletion characterised both erosional and depositional areas, and may be caused by increased water dynamics and resuspension of sediment due to anthropogenic activities. The apparent sediment accumulation rate determined with 210 Pb xs in depositional areas was estimated at 0.2–0.4 cm y −1 . In the majority of cores, 210 Pb xs inventories were lower than expected from atmospheric fallout, suggesting its export along with fine particles. The different sediment characteristics in terms of grain-size distribution and organic carbon content observed in the upper layer with respect to the deeper ones reflect the modification of the sedimentary balance in recent years. The loss of fine particles, even from sediments in depositional areas of the northern part of the lagoon, may herald changes in local sediment texture leading to a further depletion of morphodiversity, which in turn may lead to the reduction or loss of important lagoon habitats. On the whole-lagoon scale, the prevalently lithogenic elements (Al, As, Cr, Fe, Mn, Ni) decreased towards the top of the cores, reflecting the depletion of fine particles in the upper sediment layer due to winnowing in non-confined lagoon areas. In contrast, partly anthropogenic elements (Cu, Hg, Pb, Zn) increased up to the subsurface sediment layers (5–10 and/or 10–20 cm) as an effect of increasing pollutant inputs until a certain time in the past. Enrichment Factors (EF) were calculated from 9 cores, comparing concentrations in the “pre-industrial” (>100 years ago) and recent (surface layer, 0–5 cm) sediments. The mostly lithogenic elements were not enriched (EF ˜ 1), whereas the partly anthropogenic elements showed slight (Cu and Pb, EF ˜ 1.2) to significant (Hg and Zn, EF ˜ 2) enrichment. The shallow waters on the landward side (particularly close to freshwater inputs), the area nearby the industrial district of Porto Marghera and a small zone adjacent to the city of Chioggia were identified as the main pollutant accumulation sites. Mercury was the only element potentially harmful for aquatic life. Its concentration in the biologically active surface sediment layer (0–5 cm) exceeded the NOAA Effects Range-Median (ERM) value in 27% of samples, corresponding to 20% of the shallow-water surface area. The collected data set represents a valuable reference for monitoring the impact of the construction and operation of the MOSE system on the sediment features of the Venice Lagoon. [ABSTRACT FROM AUTHOR]

The distribution of microplastics (MPs) was investigated in the sediments of five sampling sites from the northern Tunisian coast during June 2017. MPs were categorized according to type, colour and size. Representative MPs from the five sites were isolated for polymer identification using Fourier Transformed Infrared Spectroscopy in attenuated total reflectance mode (FTIR-ATR). Results showed that MPs were recovered, from all sediment samples, indicating for the first time, their extensive distribution in Tunisian coast. Concentrations varied from 141.20 ± 25.98 to 461.25 ± 29.74 items kg −1 dry weight. Fibres, fragments, Styrofoam ® , pellets and films were the types registered in this study. With the exception of Menzel Bourguiba (MB), fibres significantly outnumbered plastic particles followed by fragments, Styrofoam ® , films and pellets. The predominant colours are as follows: black > clear > white > red > blue > green for fibres, blue > white > clear > red > green > yellow > black for fragments, blue > white > black > clear for films while only white pellets and Styrofoam ® were found. MPs particles ranged from 0.1 to 5 mm in length. A total of three polymer types were identified, polyethylene (PE), polypropylene (PP) and polystyrene (PS). Except for industrial pellets, the presence of MPs is likely due to the degradation of marine plastic debris accumulating in each site. This work provides original data of the presence of MPs in coastal sediments from Northern Tunisian coast. [ABSTRACT FROM AUTHOR]

Antibiotic resistance disseminating from animals and their environments is a public issue that poses significant threats to human health. In the present study, the diversity and abundance of antibiotic resistance genes (ARGs) in 15 samples from the guts and related aquaculture environments (water and sediment) of shrimp were investigated. In total, 60 ARGs, 102 ARGs and 67 ARGs primarily belonging to 13, 15 and 15 different types were detected in the shrimp gut, pond water and sediment samples, respectively. Efflux pump and target modification were the predominant resistance mechanisms in all samples. It was found that Aeromonas , Yersinia and Clostridium XlVb were significantly correlated with the distribution of the ARGs. Besides, the relative abundance of ARGs was positively correlated with the levels of mobile genetic elements (MGEs). Moreover, variation partitioning analysis showed that MGEs, contributing to 74.46% of the resistome variation, played an important role in the affecting of the antibiotic resistome than the bacterial communities and their joint effects. Collectively, this study provides comprehensive information to better understand the ARG dissemination in aquaculture environments and to improve the ecological management of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The Dagh-e-Sorkh playa is a closed basin in central Iran. The sediments of this playa were studied for sedimentologic and geomorphologic characteristics, the interaction of sedimentation mode of a terminal ephemeral fluvial-fan system and adjacent lacustrine/aeolian sediments in the area. Evaporite minerals including calcite, gypsum and halite were the most dominant minerals. The two main types (pediment and playa type) and few subtypes facies were identified. Based on the surface and subsurface study, the area was zoned and sedimentary- stratigraphic column for each zone was interpreted and six zones were characterized. These data clearly show that different conditions are dominant for the deposition of sediment and vertical changes in sedimentary facies around the area. [ABSTRACT FROM AUTHOR]

A rapid method for determining organochlorine pesticides and polycyclic aromatic hydrocarbons in soils and sediments was developed to allow pollution surveys to be performed in emergencies. The method involves microwave-assisted extraction and uses an automated identification/quantification system with a gas chromatography mass spectrometry database. A sample (3 g) is extracted with a 3:2 v/v hexane:water mixture (10 mL) for 30 min using a microwave-assisted extraction system at 120°C. The hexane extract is then cleaned using silica gel, then analyzed by gas chromatography mass spectrometry. The total analysis time is approximately 4 h. The precision of the quantitative results and accuracy of the analyte identification were determined. The total analyte concentrations were generally comparable to (61%–110% of) the concentrations determined using a Soxhlet extraction method, but the concentrations of individual high-molecular-weight polycyclic aromatic hydrocarbons were unacceptably low compared with the concentrations determined using the Soxhlet method. However, these compounds (e.g., benzo(ghi)perylene and indeno(1,2,3-cd)pyrene) were subsequently efficiently extracted using a hexane:water:ethanol mixture. The accuracy of identification was evaluated using accurate masses determined by gas chromatography time-of-flight mass spectrometry, and the mass error was 2 ppm for 21 of the 22 compounds identified using the new method. [ABSTRACT FROM PUBLISHER]

Summary: Correlation studies are an important hypothesis‐generating and testing tool, and have a wide range of applications in many scientific fields. In ecological studies in particular, multiple environmental variables are often measured in an attempt to determine relationships between chemical, physical and biological factors. For example, one may wish to know whether and how soil properties correlate with plant physiology. Although correlation coefficients are widely used, their properties and limitations are often imperfectly understood. This is especially the case when one is interested in correlations between, say, trace element content in sediments and in marine organisms, where no one‐to‐one correspondence exists. We show that evaluating Pearson's correlation coefficient for either site‐specific means or composite samples results in biased estimates, and we propose an alternative estimator. We use simulation studies to demonstrate that our estimator generally has a much smaller bias and mean squared error. We further illustrate its use in a case study of the correlation between trace element content in sediments and in mussels in Lyttelton Harbour, New Zealand. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) serve as point-source inputs for a variety of nutrients often dominated by nitrogenous compounds as a result of anthropogenic influence. These effluents can impact biogeochemical cycles in freshwater estuaries, influencing microbial communities in both the water and sediment compartments. To assess the impact of point source nutrients, a transect of sediment and pore water samples were collected from 4 locations in the Little River Sub-watershed including locations above and below the Little River Pollution Control Plant (LRPCP). Variation in chemistry and microbial community/gene expression revealed significant influences of the effluent discharge on the adjacent sediments. Phosphorus and sulfur showed high concentrations within plume sediments compared to the reference sediments while nitrate concentrations were low. Increased abundance of denitrifiers Dechloromonas , Dok59 and Thermomonas correlating with increased expression of nitrous-oxide reductase suggests a conversion of N 2 O to N 2 within the LRPCP effluent sediments. This study provides valuable insight into the gene regulation of microbes involved in N metabolism (denitrification, nitrification, and nitrite reduction to ammonia) within the sediment compartment influenced by wastewater effluent. [ABSTRACT FROM AUTHOR]

Sediment grain size analyses for 179 seabed samples in the Yangtze Estuary were conducted by both traditional (pipette and sieving) and laser (Coulter, LS-100Q, USA) methods. Our results show that the sediments in the North Channel and the upper reach of the inner Yangtze Estuary are mainly sands and silty sands, usually coarser than those in the South Channel. The deposits in the South Channel and the Northern Hangzhou Bay are mainly clayey silt. Meanwhile, silty sands cover the most northern part of the outer estuary, and are apparently coarser than the clayey silty in the southern part of the outer estuary. The sediments in the outer estuary off the South Channel mainly reflect the modern deposits, while the sediments off the North Channel are dominated by relict Pleistocene sands. As to the measurement methods, there are apparent distribution patterns of relative size from the two methods. Moreover, regression analyses for the five parameters, including mean size, median size, standard deviation, skewness, and kurtosis, were conducted to obtain reliable conversion formulas for the two methods. These can be used in future studies for comparison with historical data. [ABSTRACT FROM AUTHOR]

The recovery of the confined aquatic disposal (CAD) facility located at Malmøykalven in Oslofjord, Norway, has been assessed using an array of field measurement techniques. These methods were used prior to the disposal of dredged sediments as well as during 3 annual postdisposal monitoring campaigns. Traditional sampling to assess chemical recovery indicates that an immediate reduction in total sediment concentrations and surface sediments can be characterized as having good quality. Deposition of new material indicates that the quality of depositing material at the CAD is stabile and representative of the natural background quality in the area. Continued deposition of this material will improve the long-term chemical recovery of the CAD. A positive biological recovery of the benthic community has been observed and is expected to continue along a typical benthic succession pattern. To supplement traditional sampling, passive samplers were deployed at the CAD. Results suggest that the flux and concentrations of polycyclic aromatic hydrocarbon 16 and polychlorinated biphenyl 7 released from the CAD will continue to decrease over time. The combined results from these multiple lines of evidence indicate that the CAD and capping layer function as predicted 3 yr after the construction was completed. There is not only an improvement in the efficacy of the CAD itself but also a general improvement of the area, compared with the situation prior to disposal. Environ Toxicol Chem 2017;36:2552-2559. © 2017 SETAC [ABSTRACT FROM AUTHOR]

In this study, water, sediment and Unio mancus (Lamarck, 1819) samples were collected from Atatürk Dam Lake (Turkey) seasonally between 2015-2016 years and samples were analysed for certain heavy metal contents (Fe, Cu, Pb, As, Hg, Cr, Mn, Cd, Co, Zn, and Ni). Factors affecting heavy metals uptake and distribution have also been discussed separately. The amounts of heavy metals were quantified by an inductively coupled plasma mass spectrometer (ICPMS). The results showed that the metal concentrations in water were significantly higher than the value of standart drinking water recommended by the WHO and USEPA but metal concentrations in mussels were generally lower than the levels for mussels recommended by World Health Organization (WHO). Only levels of arsenic and lead were higher than permissible limits in all sampling points and seasons. Metal residue levels were higher in the sediments than in the water and mussel. Fe was the predominant residue in water and mussel samples as to Mn was dominant in sediment samples. Results suggest that Atatürk Dam Lake was polluted by different heavy metals, industrial activities and urban wastes for years. [ABSTRACT FROM AUTHOR]

In this study, data classification method was evaluated to increase accuracy of estimating suspended sediment load. To achieve this objective, suspended sediment in Chehelgazi and Khalife Tarkhan rivers in Kurdistan, Iran, were estimated using sediment rating curve (SRC) method in three different approaches of data classification. At first, measured data were modelled without classification. Then, data based on flow statues were divided into two series as high and low flow. Eventually, based on sediment concentration, the data were divided into low and high sediment concentration. Long-term runoff and sediment data were used to calibrate rating curve model. The estimated values were compared with recorded data and the performances of these models were evaluated using statistical criteria. The results indicated an effective role of data classification to improve estimating sediment transportation by rating curve method. In one of the stations, it was observed that due to classification based on river flow and sediment concentration, model efficiency was increased about 45% and 28%, respectively. Furthermore, in case of improving efficiency of SRC method, classifying data based on flow statues was found to be more effective than sediment concentration. The results of this study can be used to improve the management of the watershed by more accurately estimating the amount of suspended sediments transporting in the rivers draining to reservoirs. [ABSTRACT FROM AUTHOR]

Human impact on marine benthic communities has traditionally been assessed using visible morphological traits and has focused on the macrobenthos, whereas the ecologically important organisms of the meio- and microbenthos have received less attention. DNA metabarcoding offers an alternative to this approach and enables a larger fraction of the biodiversity in marine sediments to be monitored in a cost-efficient manner. Although this methodology remains poorly standardised and challenged by biases inherent to rRNA copy number variation, DNA extraction, PCR, and limitations related to taxonomic identification, it has been shown to be semi-quantitative and useful for comparing taxon abundances between samples. Here, we evaluate the effect of replicating genomic DNA extraction in order to counteract small scale spatial heterogeneity and improve diversity and community structure estimates in metabarcoding-based monitoring. For this purpose, we used ten technical replicates from three different marine sediment samples. The effect of sequence depth was also assessed, and in silico pooling of DNA extraction replicates carried out in order to maintain the number of reads constant. Our analyses demonstrated that both sequencing depth and DNA extraction replicates could improve diversity estimates as well as the ability to separate samples with different characteristics. We could not identify a “sufficient” replicate number or sequence depth, where further improvements had a less significant effect. Based on these results, we consider replication an attractive alternative to directly increasing the amount of sample used for DNA extraction and strongly recommend it for future metabarcoding studies and routine assessments of sediment biodiversity. [ABSTRACT FROM AUTHOR]

The fate of nitrogen in natural environments is controlled by anaerobic nitrate-reducing processes by which nitrogen is removed as N 2 or retained as NH 4 + . These processes can potentially be driven by oxidation of reduced inorganic compounds at oxic-anoxic interfaces. Several studies have investigated the use of Fe 2+ as an electron donor in nitrate reduction in bacterial cultures, however current information on this process in the environment is sparse. We aimed to determine whether nitrate-reducing processes in the freshwater Lake Almind (Silkeborg, Denmark) were linked to Fe 2+ oxidation. Anaerobic sediment slurries were supplemented with 15 N-substrates and electron donors (Fe 2+ and/or acetate) to characterize nitrate-reducing processes under environmentally relevant substrate concentrations and at higher concentrations traditionally used in microbial enrichment studies. Dissimilatory nitrate reduction to ammonium, DNRA, was stimulated by Fe 2+ addition in 7 of 10 slurry experiments and in some cases, denitrification was concomitantly reduced. The determined kinetic parameters (V max and K m ) for Fe 2+ -driven DNRA were 4.7 µmol N L −1 d −1 and 33.8 µmol Fe 2+ L −1 , respectively and reaction stoichiometry for Fe 2+ :NH 4 + (8.2:1) was consistent with that of predicted stoichiometry (8:1). Conversely, under enrichment conditions, denitrification was greatly increased while DNRA rates remained unchanged. Increased Fe 2+ concentrations may be exploited by DNRA organisms and have an inhibitory effect on denitrification, thus Fe 2+ may play a role in regulating N transformations in Lake Almind. Furthermore, we suggest enrichment conditions may promote the adaptation or change of microbial communities to optimally utilize the available high substrate concentrations; misrepresenting metabolisms occurring in situ . [ABSTRACT FROM AUTHOR]

We examined the vertical distributions of total organic carbon (TOC), total nitrogen (TN), total sulfur (TS), and 21 polycyclic aromatic hydrocarbons (PAHs) in a 100-cm-long sediment core collected from Lake Kitaura, a small and shallow eutrophic freshwater lake in central Japan, to elucidate changes in its aquatic environment and the input of PAHs with respect to human activity over the last 1000 years. Using a cross-plot of TOC and TS, the aquatic environment of this lake was well classified into four stages: a marine-brackish water period (≤1321 AD), a brackish-freshwater period (1394-1646 AD), a freshwater period (1726-1958 AD), and a eutrophication period (≥1971 AD). During the current eutrophication period, both TOC and TN have increased dramatically and TOC/TN (which is a useful indicator for distinguishing between aquatic and terrestrial plant sources) has decreased because algal production has markedly increased recently due to eutrophication. The vertical distributions of PAHs (which have derived primarily from combustion over the last 1000 years) showed increases in layers corresponding to periods of volcanic activity in the 18th century, as well as dramatic increases from 1971 to the present. Thus, both the aquatic environment and the input of PAHs in Lake Kitaura have been strongly affected by recent human activity. On the other hand, among all of the PAHs, only perylene-which is known to be of biological origin-was consistently formed via first-order kinetics over the period covered by the core. Its formation was barely influenced by fluctuations in the input of the precursor of perylene or how reductive the environment in the bottom water was. [ABSTRACT FROM AUTHOR]

Drinking water treatment residuals (WTRs) have a potential to realize eutrophication control objectives by reducing the internal phosphorus (P) load of lake sediments. Information regarding the ecological risk of dewatered WTR reuse in aquatic environments is generally lacking, however. In this study, we analyzed the eco-toxicity of leachates from sediments with or without dewatered WTRs toward algae Chlorella vulgaris via algal growth inhibition testing with algal cell density, chlorophyll content, malondialdehyde content, antioxidant enzyme superoxide dismutase activity, and subcellular structure indices. The results suggested that leachates from sediments unanimously inhibited algal growth, with or without the addition of different WTR doses (10% or 50% of the sediment in dry weight) at different pH values (8–9), as well as from sediments treated for different durations (10 or 180 days). The inhibition was primarily the result of P deficiency in the leachates owing to WTR P adsorption, however, our results suggest that the dewatered WTRs were considered as a favorable potential material for internal P loading control in lake restoration projects, as it shows acceptably low risk toward aquatic plants. [ABSTRACT FROM AUTHOR]

The concentration and distribution of three persistent organic pollutants (hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and polychlorinated biphenyls (PCBs)) was assessed in tidal flat sediments collected from the south bank of Hangzhou Bay, China from 2009 to 2013. Gas chromatography coupled to triple quadrupole mass spectrometry (GC-MS/MS) was used for analysis, based on United States Environmental Protection Agency methods EPA8080A, EPA8081B, and EPA3550B. The results showed that the levels of HCHs, DDTs and PCBs decreased in the order of DDTs < HCHs < PCBs, and their mass fractions ranged from 0.29-32.91, 0.09-13.19 and 0.16-4.10 μg/kg (dry mass), respectively. The levels of HCHs, DDTs and PCBs decreased slowly from 2009 to 2013, with considerably greater concentrations in winter than in spring and summer. In this study area, the concentrations of DDTs and HCHs decreased gradually towards the mouth of Hangzhou Bay, while the concentrations of PCBs were related to changes in the local economy. In addition, the sources of HCHs and DDTs were identified as atmospheric precipitation and historical residues. Finally, we predicted that PCBs pollution primarily originated from Aroclor 1254(Lot A4), which might root in the illegal demolition and stacking of abandoned paint, transformer or electronic equipment in the south bank of Hangzhou Bay. [ABSTRACT FROM AUTHOR]

An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates. [ABSTRACT FROM AUTHOR]

In this research, ecological risks for eight individual polycyclic aromatic hydrocarbons (PAHs) and ∑PAH8in surface sediments from middle and lower reaches of Yellow River are evaluated using overlapping areas of probability density curves and margin of safety (MOS), based on the toxicity data and the exposure concentrations of PAHs in sediments collected from 23 sites. In the overlapping areas of probability density curves, the risk of Ant and Pyr are the highest, then the risk level is in the order of Flua > Nap > Phe > BaP > Flu > Ace. The values ofMOS10present that Pyr (4.62 × 10−4), Ant (5.60 × 10−3), and Flua (6.4 × 10−3) have a significantly high ecological risk level, while Nap and Phe have middle-level ecological risk. As for Ace, BaP, and Flu, they pose limited risk to the ecological system withMOS10greater than 1.0. The ∑PAH8(2.66 × 10−5) is a higher risk level than that of any individual PAHs, where the probabilities of ∑PAH8in excess of the 10th percentile of the toxicity data were 86%. [ABSTRACT FROM AUTHOR]

Marine coastal areas of British Columbia, Canada are subject to a gradient of increasing anthropogenic sources from pristine areas in the north to the more urbanised areas of the south. Along the gradient, the relative contributions of polycyclic aromatic hydrocarbons (PAHs) from multiple natural and anthropogenic sources are not well understood, but concerns linger about bioavailability and consequent risks to marine biota. Composition patterns and principal components analysis (PCA) models for surface sediment and core samples collected along this transect indicate that samples from the urbanised Vancouver area have the highest proportions of tricyclic terpane, hopane and sterane biomarkers, UCM (unresolved complex mixture), the alkyl fluoranthene/pyrene and benz[ a ]anthracene/chrysene series and most parent PAHs. Those from Hecate and Queen Charlotte Straits and other locations in the Strait of Georgia have, on the other hand, higher proportions of the resolved alkanes, and petrogenic alkyl naphthalene, fluorene, dibenzothiophene and phenanthrene/anthracene series. PAH ratios clearly indicate a predominance of combustion sources for the four ring and higher parent PAHs for all the sediments. Most samples have values close to the biomass/solid fuel and liquid fuel combustion borderline for ratios of the major PAHs, but liquid fuel combustion input dominates closer to urbanised locations. Ratios also suggest similar pyrogenic and petrogenic inputs between central Hecate Strait and reference sediments from Hecate Strait through to Queen Charlotte Strait, which indicates that biomass combustion and immature coal formations are the major putative respective sources for the reference areas. Alkyl PAH ratios for the C 3 and C 4 naphthalenes, C 2 and C 3 phenanthrenes and 3- and 2-methylchrysene, reflecting terrigenous/vascular plant sources and petroleum maturity, exhibit marked differences between Comox bituminous coal and Alberta Sweet Mixed Blend (ASMB) oil and reveal that the petrogenic input in all of the sediments is non-biodegraded. Ratios of these alkyl PAHs with multiple substituents indicate that the sediment samples in the northern Strait of Georgia closest to the Comox coal field receive relatively constant input of eroded coal, while those in the southern Strait of Georgia and Vancouver Harbour show a composition closest to ASMB oil. PAHs associated with liquid fossil fuel combustion and petroleum discharges adjacent to urbanised areas are expected to be fully bioavailable to marine food webs, while the char from biomass combustion and coal from immature deposits in more remote areas would have limited bioavailability. This implies that biota in remote areas of Hecate Strait/Queen Charlotte Sound are likely not adapted to the presence of oil and thus would be more sensitive to exposure to spilled oil than those in the more impacted environments in southern British Columbia. [ABSTRACT FROM AUTHOR]

The paper presents data on organic carbon concentrations in riverine suspended matter and surficial bottom sediments measured in the estuary of the Razdol'naya River during the period of ice cover (February 2010). In the suspended matter, humic substances and phytoplankton accounted for 30% and 14% of total organic carbon, respectively. The concentration of humic substances in riverine suspended matter was determined for the first time by spectrophotometry. The concentration of phytoplankton carbon was calculated from the chlorophyll-a content. Concentrations of organic carbon, humic substances, and chlorophyll-a were measured in the surface sediment layer. The proportions of these three components show no marked variability with an increase in salinity to 23‰. The degree of humification in bottom sediments was about 52%. Organic carbon concentrations were almost an order of magnitude lower and the proportion of bioavailable (nonhumified) carbon was two times lower in the bottom sediments than in the riverine suspended matter. [ABSTRACT FROM AUTHOR]

[Display omitted] • There are obvious differences in the sediment of different parts of ginseng. • Identified the key components that caused the turbidity of the aqueous extract. • The contribution of each chemical component to sediment has been clarified. Sediment is a key issue in the production and marketing of plant beverages, as is ginseng beverages. The formation of sediment in ginseng beverages is a gradual process. This work describes the formation of sediment from different parts of ginseng and describes the color and clarity of the liquid and the amount and morphology of the sediment. The results showed there are significant differences in the sediment formation speed, morphology and transmittance for the aqueous extracts prepared from different parts of ginseng. The amounts of sediment generated from the different parts of ginseng is as follows: main root > rhizome > fibrous root. Free amino acids, Ba, Ca, Ni, and Sr concentrations are significantly and positively correlated with the transmittance. The total saponins, Al, Fe, and Mn concentrations are significantly and negatively correlated with the transmittance. There are obvious crystals and more Ca in the fibrous root sediment. We analyzed and compared the chemical components in the sediment and extract. The results show that the main components of the sediment are carbohydrates and protein. According to the partition coefficient the contents of protein, ginsenosides (Rb1, Rb2, Rb3, Rf) and some ions (Al, Fe, Ca, and Na) contribute more to the formation of the sediment than the other investigated components. [ABSTRACT FROM AUTHOR]